Police appealed on Friday to protesters in the China-ruled city not to disrupt the lowest-tier, district council elections, held every four years, pointing to nearly six months of protests and street clashes that officials say have brought the city to the "brink of total breakdown".

"We have to ensure voter safety and let them vote without any interference," Police Commissioner Tang Ping-keung said at a briefing on Friday after a two-day lull in violence.

He said police would "deploy high-profile patrols" near polling stations. There have been no publicised threats against voters or polling stations.

The protests started over a now-withdrawn bill that would have allowed people to be sent to China for trial but which soon evolved into calls for full democracy.

A man stabbed and wounded pro-Beijing lawmaker Junius Ho earlier in November.

Jimmy Sham, a leader of Hong Kong's pro-democracy Civil Human Rights Front, was beaten by men with hammers in October after his group organised mass rallies against the extradition bill.

A knife-wielding man bit off part of pro-democracy district councillor Andrew Chiu's ear at the beginning of November.

District council candidate Clement Woo said members of his pro-establishment camp had experienced violence and intimidation.

"How can the election be a fair one if the atmosphere is like this?" Woo told Reuters.

Veteran democratic politician Emily Lau said there was a "real concern that the campaign could get violent and nasty, with candidates and offices from both camps getting injured and vandalised".

The government urged protesters not to disrupt the vote.

"We do not want to see the postponement or adjournment of the polling unless absolutely necessary," said Patrick Nip, Secretary for Constitutional and Mainland Affairs.

A record 1104 people are running for 452 district seats and a record 4.1 million Hong Kong people have enrolled to vote for district councillors, who control some local spending, and whose daily decision-making spans a range of neighbourhood issues including recycling, transport and public healthcare.

Some of the seats that were once uncontested and dominated by pro-Beijing candidates are now being fought for by young pro-democracy activists.

Although most nominations were approved, authorities barred prominent activist Joshua Wong from running.

Hong Kong leader Carrie Lam has the power to cancel the elections up to 24 yours before they begin.

Meanwhile, at least eight protesters who had been holding out at a trashed Hong Kong university surrendered on Friday, while others searched for escape routes past riot police who surrounded the campus but said there was no deadline for ending the stand-off.

The siege at the Polytechnic University on the Kowloon peninsula appeared to be nearing an end with the number of protesters dwindling to a handful, days after some of the worst violence since anti-government demonstrations escalated in June.

Australian Associated Press